The detentions come a day ahead of a planned demonstration scheduled for this weekend – which would be the 13th weekend in a row that protests have occurred. Police have declined permission for the rally, citing public safety concerns – but protesters are expected to gather regardless.

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Demosisto member Agnes Chow has also been arrested

Well-known independence campaigner Andy Chan said he too had been detained by police, while trying to board a flight from Hong Kong to Japan on Thursday night.

He was arrested on suspicion of rioting and assaulting a police officer, according to local outlet HKFP.

Some 900 people have been arrested since protests began in early June, triggered by a controversial extradition bill, police said on Wednesday.

With the bill now suspended, the rallies have evolved into a broader movement demanding democratic reform and an investigation into alleged police brutality.

The protests have frequently escalated into violence between police and activists, with injuries on both sides.

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Media captionHow Hong Kong got trapped in a cycle of violence

There are also growing fears that China could intervene in the protests by sending in mainland troops. On Thursday, these concerns were fuelled after China’s military moved a new batch of troops into Hong Kong. Chinese state media described it as a routine annual rotation.

The recent protests have been characterised as leaderless, but Joshua Wong is a figurehead for many due to his leading role in the 2014 rallies known as Hong Kong’s “Umbrella protests”.

His latest arrest comes just weeks after he was released from prison in June, after serving time for his role in the 2014 protests.